Canard type airplane



Filed .July 5, 1929 J. BLoNDlN 1,839,194

CANARD TYPE AIRPLANE 2 Sheets-Sheet 1 Jan. 5, 1932.

J. BLoNblN I 1,839,194

CANARD TYPE AIRPLANE Filed July 5, 1929 2 Sheets-Sheet 2 l Avy/enviar;j2me/127e BZoWdz'w,

Patented Jan. 5, 1932 PATENT OFFICE JOSEPH BLONDIN, OF LOS ANGELES,vCALIFORNIA CANARD TYPE AIRPLANE Application led July 5,

This invention relates to aircraft and particularly to airplanes of thecanard type comprising main lifting surfaces or wings and a loaded orweight carrying front elevator supported by a framework extendingforward of the main wings;

Aviation history chronicles'many canard types of airplanes which flewmore or less successfully and all of which were characterized 1o bysuperior qualities of fore-and-aft stability compared with other typesof airplanes. But they were all inferior in response to rudder action;i. e., to being steered sidewise.

An object, therefore, of this invention is to successfully modernize thecanard-type airplane retaining and improving its qualities offore-and-aft stability, and endowing it with eiiicient rudder-actionwhich it has heretofore lacked.

Pioneer canard-type airplanes were also defective in that element ofstructure which was depended upon to support the front elevator. In thecase of biplanes such element was an Outrigger frame attached to andprojecting forward from the wings. Such outrigger-frames were inherentlyweak because of length and lightness, and lack of 'resistive factor tolateral and tortional stresses. In the case of monoplanes such elevatorcarrying element was a central, quadrangular or box-- truss frameforming an integral extension of the nacelle orV car and was supportedclear of the ground by the running gear which` consisted, generally, oftwo side wheels at the rear portion of the frame, and one central wheelset far forward on the frame. This frame, while capable of being mademore rigid and stronger for a givenweight than the biplanes Outriggerwas, however, handicapped by being made to also carry the said forwardwheel unit of the running gear thereby being forced to absorbthe violentstresses placed on the wheel-unit at take-olf and landing, and groundrunning, and these stresses werel imposed upon said box-frame close toits extreme forward end,A or at `its point of free overhang-ff orunsupported leverage.

A further object, therefore, is to provide a front-elevator supportingstructure of 50 maximum rigidity and resistance to all ver- 1929. SerialNo. 376,280.

tical, lateral and' torsional stresses that might be imposed by theelevator, and to eliminate the conventional forward wheel-unit as usedin the past, thus relieving the forward extending, free overhang portionof the frame from all landing stresses and limiting it' to its single,proper function of supporting the front elevator. To this end I haveinvented and provided an inverted, triangular-trussed keelframe whichnot only supports the front elevator but underlies and directly andincidentally supports all other constructional and operative elements ofthe airplane proper. By the present invention for over two-thirds of itslength the keel frame supports the nacelle orcar and is in turnreinforced and strengthened by the rigidity and inertia of the car andits loads.

A further object is to provide a skid frame of inverted triangular formwhose rear and lowermost end is adapted to engage the ground whenlanding and further, whose apex-beam or keel will act. as a runner atits rearmost end and at any other portion in its length, in emergency,such as might occur if 'I5 the wheels dropped into a ditch or thefurrows of a plowed field. l Note that in either case this inventiondesigns the sln'd-feature to function' directly under the car whoserigidity and inertia will absorb all landing stresses.

More directly, the landing gear proper consists, here, of the rearmostand lowermost portion of the triangular keel-frame in combination with aplurality of side wheels widely spaced laterally from the sides of thecar of the airplane; the keel-frame having a yield'able shoe. Allprevious canards were characterized by the employment of a singleelevator surface carried forward of the machines center of gravity,whose carrying ca-l pacity, as a wing, and directional capacity, as anelevator was depended upon to govern the inherent stability, trim andclimbing and diving maneuvers of the airplane.

An additional obj ect of this invention .is to supplement the abovereferred to conventional front elevator and materially improve thecontrol of such canard type planes by adding a rear elevator carriedrearward of the machines center of gravity and hinged to the rearwing-bar of the main lifting planes; this being entirely originalconception. in canard type airplanes, and greatly enhancing control ofthe machines fore and aft balance and direction, and made effectivedistinctively by my provision wherein the center of gravity of themachine, in flight, is maintained forward of the main liftmg wings andnot below as heretofore the Case.

Another object is to provide a superior means for aircraft steering,particularly canards, around their vertical axis. All previous canardplanes were deficient in sidewise steering action, their lack of properkeel or vertical lin to complement their rudder surface being adjudgedthe reason for the defect.

.Now, in the first place, none of the pioneer canards, actually builtcarried their center of gravity sufiiciently forward.

The location of this fundamental governing point was. in most cases,positioned directly under the wings leaving insufficient leverage forthe rudder to act upon. The operation of a single vertical rudder, sohandicapped, resulted more in an outward skid then a true turn-a skidwhich immediately entailed loss of lateral stability, followed bystalling or diving effects which quickly defamed the canard principle ofdesign.

Remedy of this defect usually took the form of extra vertical -surfacesor fins placed forward of the wings upon the framework which su portedthe front elevator. These furnishe the needed fulcrum for the rudder toact against but they, at the same time, furnished an added fin surfacewith long leverage from the machines center of gravity for any and evervside gust or current of wind to act upon. Thus the rudder action wasagain minimized-or even nullified--the machine in such case being turneddown Wind with a consequent greater loss of lateral stabilitv than inthe former case. Also, a single rudder located followingr the exactlongitudinal axis of any vessel acts detrimentally in the sense that thedrag component serves to retard the speed of the vessel and.consequently, to reduce fluid reaction against the rudder surface;action whose efficiency in-l creases as the square of the speed of thevessel. Obviously, such rudders contribute only the side component orthrust of their overall possible steering eiciency. I seek to obtain amaximum effective steering action through, first-placing the center ofgravity of the machine at a point situated at least 25% of the wingchord in front of the leading edge of the main wings thereby increasingthe rudders leverage to said center: secondby provision of twin ruddersoperative outward only as to the ships longitudinal axis:third-provision of means to operate each twin rudder independent of theother so that but one is effective on turns while the other lies in thebed of the wind or at zero angle to the fiight line: fourth-theprovision of rudders placed off the longitudinal axis of the machine ata considerable distance so that each rudder acts jointly in response toside thrust and to backward drag as Well, on lever arms whose magnitudesare measured forward to the center of gravity of the machine andlaterally to the long axis respectively: fifth-the provision of apreponderance of constructional vertical surfaces rearwardly of thecenter of gravity of the machine so that all side-gusts or currents ofwind, in flight, will tend to turn the machine into the wind; thecorrect position for maintaining the stability of the machine.

A still further object is to provide means to utilize the drag effect ofthe rudder conjunctively to reduce the momentum of the machine whenlanding and thus shorten the run after first touching ground. To thisend means are provided for separate turn and for concurrent brake actionthrough the instrumentality of rudders.

Still another object is to provide window frame struts so disposed as torise vertically from lateral beams from the chassis to superjacent maincantilever wings and to perform the important function of supporting thewing at a material distance outward from the nacelle or car, thusreinforcing the cantilever wing by reducing the length of its freeoverhang. In full cantilever wing machines the overhang extends from thefuselage or car side to the extreme tip of the wing.

In the present disclosure the wings overhang extends only from thewindow-frame struts outward to the tips of the wings; a reduction inlength furnishing' greater stiffness to the wings and reinforcementagainst compression and bending strc-'ses in the intcrnal structuralnwmhers of' the wings.

My invention has for particular object-1 therefore, first--theimprowuuut of thc air plane type of alrciaft and -fsl till :ill fanardtype airplanes by infurlfvung the keel frame as '1u element ofthelanding gear and to unite, .strengthen and .support all other elementsof the machine; sccfutlmthc provision of a canard type which places` thecenter of gravity entirely forward of its main lifting planes` andthird-the provision of operative means improving the stability and thecontrol of the balance and of the flight direction of the machine.

Other objects, advantages and features of construction, combination anddetails of means and mode of operations will be made manifest in theensuing description of the herewith illustrative embodiment; it beingunderstood that modifications, variations and adaptations may beresorted to within the spirit, scope and principle of the inventiffn asit is more directly claimed hereina er.

ills

Figure 1 is a plan of the airplane. v Figure 2 is a side elevationthereof. p

Figure 3 is a front elevation, and

Figure 4 is a diagram showing the relative position of the rudders tothe ships center of gravity. v

In the illustrated ship a front elevator A is disposed well ahead of themain liftin surface or wing B; both being solidlyxe on a skeletonchassis into which is built the nacelle or car N. The skeleton extendsWell forward from the car and is characterized by an inverted triangularor V-section keelframe K which presents a bottom, longitudinal apex-beamor keel K the full length of the ship; having at its rearend a hingedheel piece P supported yieldably by a bow spring P based on the rear endof the body frame.

The wings include spaced upper crossbeams I-I on the top of the cabin ofthe car N and each Wing is secured to the top stringer of respective,outboard, vertical windowframe struts J whose posts stand on laterallyprojecting, transverse beam I- which thus serve to greatly strengthentheoverhead wing structure.

The intraspaces of the window-frame struts J are provided withfin-surfaces L in front of rudders E hinged to the vertical, rear postsof the struts; the latter having dia onal braces which reinforce and stien the fin frames J and form trusses whose king post is the nacelle orcar.

Above the forward or nose part of the keel-frame K is a supplementaryV-frame K which materially stiifens and reinforces the frame K as thesupport for the front elevator and incidentally forms a harmonizingsuperpart for the keel-frame.

A notable feature of this airplane is the arrangement of the main wing Bat the extreme rear of the chassis and the placing of the car and thefront elevator to produce the center of gravity of the machine wellforward of the main wing; preferably at a minimum distance equal to 25%of the wingchord, andbeing indicated by the point G; whereby to achieveinherent stability.

The ship is provided with ground wheels W widely spaced from the sidesof the keelframe and with the keel-beam K or heel` P providing forthree-point landing contact and rest supports. The Wheels are forward ofthe rear end of the frame K and should they drop into surfacedepressions the keel K comes into effect as a sliding skid.

The-rudders 'E are independent and are operated by independent foottreadles F so that only that rudder is actuated which is on the side ofthe ship relative to an intended turn; the right foot controlling theright rudder for a right turn and the left foot for a left turn in theusual manner. Another advantage of this system is that, at will, the

l pilot may throw out both rudders at one time v with the result that adecidedbraking effect isaccomplished; this being effected by pressure ofboth feet on the rudder controls at the to the front elevator A, and arear elevator.

surface or flap B hinged to the trailing edge of the plane B andconnected to the front flap A by a control means of conventional formoperative to concurrently tilt the flaps in opposite directions; i. e.the forward one up and the latter down to pull the nose down and viceversa to raise the nose, so that each flap acts with a cooperativemovement about the-center of gravity G of the machine.

It will be noted that there is no material i vertical surface at thenose ofthe fore-rig frame carrying the front elevator means thuseliminating objectionable counteraction by side pressure of the air whenturning and avoiding side drift of the head due to lateral air currents.

The driving propeller is here shown as at vthe rear of the car N.

In the take-off position the machine rests on its three-point baseP-W-W, with the nose of the ship directed well up from the ground lineY.

Lateral stabilizing ailerons O are hinged to the main wing B outward ofthe medially dis osed rear elevator element B.

- hat is claimed is:

1. In a canard-type airplane, a triangular, trussed skeleton keel-framewhose members are permanently attached to form a unitary longitudinalgirder with its apex-beam lowermost and whose upward base forms aplatform supporting at its forward `end a front elevator, at its medianportion supporting a superimposed car and its y.rear end having asuperimposed main`wing structure the 1nverted beam forming a landingtail.

2: In a canard airplane, an integral triangular, trussed keel-framewhich underlies and supports the machines front elevator surfaces and asuperimposed car and propel ling means and main wing, and lateral iinframes carried by the keel-frame and having trailing rudders; saidframes forming outboard supports for centil-ever parts of the wing.

3. In a canard airplane, a triangular-section skeleton keel-frame withits apex-beam downward and constituting a ship-length keel and itsupward base forming a platform for superimposed planes and superim osedcar structure; the rear end of the said am forming onepoint of landingand resting support for the airplane.

4. In a canard airplane, a triangular-section, trussed keel-frame withits apex-beam downward and forming a ship-length keel, and asupplementary, triangular nose frame with its base imposed on the upwardbase of the keel frame.

5. In a canard airplane, a triangular, trussed keel-frame with itsapex-beam downward and whose extention represents the over-all length ofthe airplane, the rear end of the said beam formin a landing support,and wide spaced groun wheels at the sides of the frame and forming withthe rear end of the beam a three-point landing and standing support.

6. In a canard airplane, a fixed forward, elevating plane, a rearwardmain plane, and cooperative elevator flaps on said planes andrespectively fore and aft of the ships center of gravity.

7. A canard airplane having, in combination, a front elevator having atrailing edge flap, and a main wing havinvr a trailing edge Hap coupledto the front ap for coaction with 'respective movements in oppositedirections.

8. A canard-type airplane in which the center of gravity is forward ofthe leading edge of the main plane at a minimum distance equal to 25% ofthe chord of the wing, and having elevator means including control flapsfore and aft of the center of gravity.

9. In a canard airplane, vertical rudders having laterally outboardsupports and spaced beyond the respective sides of the long axis of themachine and operative separately to make a respective turn of themachine; the idle rudder being free to hang at zero angle to the line offlight and adapted for concurrent operation in opposite outwarddirection to serve as brakes, the braking rudders being disposedrearward of the center of gravity of the machine.

10. In a canard airplane, a pair of vertical rudders each offset fromthe longitudinal axis of the machine and rear of its center oi gravityand separately operative; whereby the active rudder induces a backwarddrag acting on a leverage measured sidewise from the rudder post to thesaid axis and simultaneously induces a side thrust acting on a leveragemeasured forward from the rudder post to the center of gravity of themachine so that each rudder has a double turning couple in steeringaction and means for concurrently turning the rudders in oppositedirections outwardly as brakes 'ective rearwardly of the center ofgravity of the machine.

11. In a canard air lane, a chassis including spaced, horizonta beamsextending laterall of the ships axis, outwardly spaced win ow-framestruts standing on said beams and whose intra-frame spaces have finsurfaces; the bottom stringers of the frames bein attached to said beamsand whose' top stringers are secured for their length to the arch of theairplanes main wing; said frames reducing the length of the freeoverhang of the wing structure.

12. In a canard air lane, a chassis including spaced, horizonta beamsextending laterally of the ships axis, outwardly spaced window-framestruts standin' on said beams; the bottom stringers of the frames beingattached to said beams and whose top stringers are secured for theirlength to the arch of the airplanes main win said frames reducing thelength of the ree overhang of-thc wing structure.

13. In a canard airplane, a main wing and rudder supports fixed theretolaterally of the ships axis, one on each side and rear of the shipscenter of gravity, and independently operative rudders on said supports,and means to set the rudders concurrently as brakes.

JOSEPH BLONDIN.

